Membrane Switches

You may not be familiar with the term membrane switches, but chances are good that you have used them many times in your life and would know one as soon as you saw one.

In simple terms, membrane switches are electrical switches used for turning on and turning off a circuit. They differ from mechanical switches, however. Mechanical switches, such as those used for lights or lamps, are usually made of copper and plastic parts that actually move and engage with something else. Membrane switches are actually a circuit printed on a PET.

PET stands for Poly Ethylene Terephthalate. This is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers. It is one of the most important raw materials used in man-made fibers and it has many uses outside of electronics.

Membrane switches use this material in a special way. A membrane switch usually consists of 2 to 4 layers of PET. The first layer of PET will have the circuit printed on it. The second layer acts as a spacer and this layer can be paper or PET. The third layer acts as the circuit closer. And the fourth layer, which is the layer you see and touch, is the front panel.

The most common types of uses for membrane switches are in such devices as microwave ovens, air conditioner control panels, TV remote controls, and other devices.

In general, they look like small illustrated boxes. There is a certain feel to these switches that are unique to them. In some cases, embedded snap domes are added to give the user a better feel when the switch is pressed. Many people in the early days of membrane switches complained that they could not tell when the switch was actually activated or de-activated. This had nothing to do with the usefulness of the switch itself; it was just a human touch response issue. Since then, manufacturers have been working to give these unique devices a more "solid" or snappy feeling when pressed.

Membrane switches have many uses and they are very affordable to manufacture, which may be one reason they are used so often. Another benefit is that they are easy and fast to manufacture once the initial layout is set up. It is basically a matter of stacking the layers atop one another and then sealing them.

Membrane switches may or may not be water proof. This is something you should look into if you are planning to use them for any type of projects. There are online catalogs available that will help you select the correct types of membrane switches for any project.